A recent study published in Nature Communications examines how the primary ingredient in marijuana known as delta-9-tetrahydrocannabinol (THC) can potentially have adverse effects on the specialized brain immune cells known as microglia within teenage brains. Microglia helps build synaptic connections during adolescent years and this study holds the potential to help scientists and the public better understand the long-term risks associated with cannabis use, either through smoking or direct consumption of cannabis products.
For the study, the researchers used genetically engineered mice to analyze the effects of THC on their microglial cells during adolescence. The genetic engineering involved a mutation that mirrors genetic risks for a specific psychiatric disorder found in humans, with non-engineered mice acting as the control group.
In the end, the researchers found a decrease in microglia in the genetically engineered mice was 33 percent greater than mice in the control group. Additionally, the team observed the decrease in microglia was specifically prevalent in the prefrontal cortex of their brains, the region of the brain responsible for regulating specific executive functions such as decision making, social behavior, and memory in both mice and humans. The team administered social memory tests for both groups of mice, finding the genetically engineered mice scored 40 percent lower than the control group.
“This kind of study is critical right now because marijuana is becoming more mainstream, and we are just beginning to understand how it affects the brain immune cells,” said Dr. Yuto Hasegawa, who is a research associate of psychiatry and behavioral sciences at the Johns Hopkins University School of Medicine and lead author of the study.
For next steps, the researchers aspire to learn more about the molecular behavior of microglia, with the long-term goal of exploring the connection between marijuana and specific psychiatric disorders, including schizophrenia.
“More research is needed, but we strongly advise caution in marijuana use by teenagers,” said Dr. Atsushi Kamiya, who is a professor of psychiatry and behavioral sciences at the Johns Hopkins University School of Medicine and a co-author on the study.
What new discoveries will researchers make regarding marijuana and its impact on the brain in the coming years and decades? Only time will tell, and this is why we science!
As always, keep doing science & keep looking up!
Sources: Nature Communications, WebMD, National Library of Medicine, EurekAlert!
